photos class 3 class 2 class 1 j-lead componentsipctraining.org/demos/pdf/drm-smt-f.pdf · j-lead...

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© IPC 2015 3000 Lakeside Drive, Suite 309-S Bannockburn, IL 60015-1219 +1 847.615.7100 (tel.) +1 847.615.7105 (fax) www.ipc.org • email: [email protected]

All rights reserved under both international and Pan-American copyright conventions. Any copying, scanning or other reproduc-tions of these materials without the prior written consent of the copyright holder is strictly prohibited and constitutes infringement under the Copyright Law of the United States.

IPC-DRM-SMT Rev. F • 3.15 2m Rev. E • 7.10 3m

Rev. D • 11.08 4m Rev. D • 11.05 5m Rev. C • 9.01 3m Rev. B • 4.00 3m Rev. A • 3.99 5m

1st printing 7.98 5m

®

Association Connecting Electronics Industries IPC DRM-SMT-F

References:IPC-A-610 Rev. F – July 2014

®

Association Connecting Electronics Industries

Area Array Components

Chip Components

Class 1Class 2

J-Lead Components

Gull Wing Com

ponentsClass 3

Photos

1

TABLE OF CONTENTS

Introduction 2

Acceptance Criteria 2

Lead Free 2

Classification 3

Terminology 4

Chip Components Class 1 Dimensional Criteria 6

Class 2 Dimensional Criteria 8


Solder Conditions—Photos 12

J-Lead Components Class 1 Dimensional Criteria 18




Gull Wing Components Class 1 Dimensional Criteria 28




Area Array Components Ball Grid Arrays (BGA) 38

Bottom Termination Components (BTC) 40

Class 1Class 2

Class 3

32

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Chip Components

J-Lead Components

Gull Wing Com

ponentsIntroductionThis Surface Mount Solder Joint Evaluation Training and Reference Guide provides visual examples of conditions found in surface mount solder joints for rectangular chips, J-leads, gull-wings, BGAs and BTCs. It also defines the dimensional acceptability requirements for each, as determined by industry consensus standards This manual references and illustrates por-tions of the following document:

IPC-A-610 Rev. F, Acceptability of Electronic Assemblies, which illustrates the requirements for many types of solder connections.

Acceptance CriteriaIn this Training and Reference Guide, minimum and maximum dimen-sional acceptance criteria are shown for each class of component type. Solder joints falling outside these parameters will be deemed as unacceptable, according to the standards set in the IPC-A-610.

A target example is also given to show the ideal case scenario. Photographs of various solder conditions follow the dimensional cri-teria for each component type.

Notes:Accept and/or reject decisions must be based on applicable documentation, e.g. contract, drawings, referenced documents, and specifications such as the: IPC-A-610 and IPC J-STD-001.

Lead Free Soldering The primary difference between the solder connections created with processes using tin-lead alloys and processes using lead free alloys is related to the visual appearance of the solder.Acceptable lead free and tin-lead connections may exhibit similar appearances, but lead free alloys are more likely to have:

- Surface roughness (grainy or dull) - Greater wetting contact angles*

All other solder criteria are the same.

*Wetting cannot always be judged by surface appearance. The wide range of solder alloys in use may exhibit from low or near zero degree contact angles to nearly 90 degree contact angles as typical.

Pb Denotes Lead Free

ClassificationSurface mount solder joint requirements are divided into three classes depending on the ultimate use, life expectancy and operating envi-ronment of the electronic assembly. These classes are as follows:

Class 1—General Electronic ProductsConsumer type products, suitable for applications where the major requirement is how it functions, not necessarily for extended life, reli-ability of service, or cosmetic perfection.

Class 2—Dedicated Service Electronic ProductsCommercial type products, where continued performance and extend-ed life is required and for which uninterrupted service is desired but not critical. Typically, the user environment is not extreme in such things as temperature or contamination, and would not cause failures.

Class 3—High Performance Electronic Products Products where continued high performance or performance-on-demand is critical, equipment downtime cannot be tolerated, end-use environment may be uncommonly harsh, and the equipment must function when required, such as for life-support, flight control, and other high-reliability systems.

Note:The inspector does not select the class for the part under inspection. Documentation which specifies the applicable class for the part under inspection should be provided to the inspector.

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TerminologyBelow are definitions that may be helpful in describing surface mount solder joints (also see: IPC-T-50):

Adhesive – In surface mounting, a glue used to adhere surface mount components to the printed wiring board.

Area Array Components – Components with terminations arranged in a grid pattern on the bottom of the package, including Ball Grid Arrays and BTCs (Bottom Termination Components such as QFN, DFN, LGA, etc.)

Assembly – A number of components, subassemblies, or combinations thereof joined together on a printed wiring board.

Blow Hole – A void in the solder joint caused by gas escaping from the molten solder.

Body – The non-metallized, or non-leaded part of any electronic component.

Chip – Rectangular “Chip” Component, a surface mounted electronic component with terminations, or metallized contact areas instead of leads.

Cold Solder Connection – A solder connection that exhibits poor wetting and that is characterized by a gray, porous appearance.

Component – An individual part or combination of parts that, when together, perform an electrical function.

Component Mounting – The act of attaching components to the printed wiring board, or the method in which they are attached.

Conductor – A single electrically conductive path in a larger conductive pattern.

Contact (Wetting) Angle – The angle formed by the edge, or meniscus, of the solder fillet on the surface of the land.

Defect – A condition failing to meet acceptability requirements, or is otherwise cause for rejection.

Dewetting – A condition that results when molten solder coats a surface and then recedes to leave irregularly-shaped mounds of solder that are separated by an area that is covered with a thin film of solder, and with the basis metal not exposed

Disturbed Solder Connection – A solder connection that is characterized by an appearance caused by motion between the metals being joined while the solder was solidifying.

Excess Solder Connection – A solder connection that is characterized by the complete obscuring of the surfaces of the connected metals and/or by the presence of solder beyond the connection area.

Flux – A compound that, when heated, promotes the wetting of a base metal by molten solder.

Flux Residue – A flux-related contaminant that is present on or near the surface of a solder connection.

Gull Wing – A type of surface mount component lead that is bent in a configuration similar in shape to a seagull's wing.

Heel – The lowest bend in any surface mount lead, just before the lead makes actual contact with the land.

J-Lead – A type of surface mount lead that is bent down and under the component, forming the shape of the letter “J.”

Knee – The uppermost bend of a component lead, closest to the component body.

Land – A portion of a conductive pattern that is usually used for making electrical connections, for component attachment, or both.

Lead – A length of insulated or uninsulated metallic conductor that is used for electrical interconnections.

Nonwetting – The partial adherence of molten solder to a surface that it has contacted and basis metal remains exposed.

Pinhole – A small hole that penetrates from the surface of a solder connection to a void of indeterminate size within the solder connection.

Process Indicator – A detectable variation in quality, other than a defect, that may be a reflection of improper material, equipment, personnel or process.

Residue – Any visual or measurable form of process-related contamination.

Solder – A metal alloy with a melting temperature that is below 427°C (800°F).

Solder Ball – A small sphere of solder adhering to a laminate, resist, or conductor surface—generally occurring after wave or reflow soldering.

Solder Bridging – The unwanted formation of a conductive path of solder between conductors.

Solder Fillet – A normally-concave surface of solder that is at the intersection of the metal surfaces of a solder connection.

Solder Paste – Finely divided particles of solder, with additives to promote wetting and other properties, suspended in a cream flux. The cream holds the surface mounted device in place until reflow soldering.

Solderability – The ability of a metal to be wetted by molten solder.

Soldering – The joining of metallic surfaces with solder without the melting of the base material.

Target Solder Condition – An ideal solder connection, though not always achievable or necessary. One that is feathered-out to a thin edge, indicating proper solder flow and wetting action. With no sharp protrusions of solder or evidence of contamination.

Termination – The metallized area of a chip component, the metallic lead of a component, or the land or terminal where a solder connection is formed.

Toe – The end or tip of a lead on a surface mount component.

Tombstoning – The complete lifting of a chip component, with one end having no solder connection to the land.

Webbing – A continuous film or curtain of solder that is parallel to, but not necessarily adhering to, a surface that should be free of solder.

Wetting – The formation of a relatively uniform, smooth, unbroken film of solder to a basis metal.

Chip Components

Class 1

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End Joint Width (C)The width of the solder joint at

its narrowest point must be a minimum of 50% the width of the

component termination (W), or 50% of the width of the land (P), whichever is less.

End Overlap (J)Some amount of overlap between the component

termination and the land is required for minimum

acceptance.

Solder Thickness (G)The minimum distance

between the land and component termination is

not specified. Only a properly wetted fillet must be evident.

Fillet Height (F)Wetting is evident on

termination’s vertical surfaces as a minimum fillet height.

Fillet Height (E)The solder may overhang the land, and extend onto

the top or side of the termination, but not touch the top or side of

the component body, as a maximum fillet height.

End Overhang (B)Any part of the component

termination extending beyond the land is unacceptable.

Side Overhang (A)The component may overhang the

side of the land a maximum of 50% of the width of the

component termination (W), or 50% of the width of the land (P),

whichever is less.

Chip Components • Class 1

This photo represents an ideal surface

mount solder joint for any class of

rectangular chip component.

Notes: Solder joints are semi-transparent to show relationship between land and termination. Side Overhang, Dimension (A), must not violate minimum electrical clearance. Minimum Side Joint Length, Dimension (D), is not required for chips, only a properly wetted fillet must be evident. The references below are applicable to the dimensional criteria for 1-, 3-, or 5-side termination Chip components.

References: A-610F: 8.3.2, Table 8-2; 8.3.2.1 through 8.3.2.8

Acceptance Criteria

Acceptance Criteria

Target Condition

Chip Components

Class 2

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Acceptance Criteria


its narrowest point must be a minimum of 50% the width

of the component termination (W), or 50% of the width of the

land (P), whichever is less.

Fillet Height (F)Wetting is evident on

termination’s vertical surfaces as a minimum fillet height.




End Overhang (B)Any part of the component

termination extending beyond the land is unacceptable.



component termination (W), or 50% of the width of the land (P), which-

ever is less.

Acceptance Criteria

End Overlap (J)Some amount of overlap between the component

termination and the land is required for minimum

acceptance.




Chip Components • Class 2Target Condition

Chip Components

Class 3

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Acceptance Criteria


its narrowest point must be a minimum of 75% the width of the


whichever is less.

Fillet Height (F)The minimum fillet height

must extend at least 25% of the height of the component

termination (H)*, or 0.5 mm (0.02 in.), whichever is less.

*Including any measurement for solder thickness (G).




End Overhang (B)Any part of the component termina-

tion extending beyond the land is unacceptable.




whichever is less.

Acceptance Criteria

End Overlap (J)A 25% overlap contact between

the component termination and the land is required for

minimum acceptance.









Chip Components • Class 3Target Condition

Chip Components

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The following pages show photographs of some of the major solder defects and process indicators for surface mounted Chip components.

These examples each contain a description as well as a reference to the appropriate section in the IPC-A-610F.

Solder fails to meet minimum fillet height. No evidence of properly wetted fillet.

Defect, Class 1, 2, 3 Reference A-610: Section 8.3.2.6

Solder extends onto the top or side of the component body.


Solder has not adhered to the land or termination.

No metallic bond.

Defect, Class 1, 2, 3Reference

A-610: Section 5.2.4

Molten solder coats surface then pulls back, leaving only

a thin film of solder cover-ing the land in some areas,

and irregular mounds of solder in others.


A-610: Section 5.2.6, Fig. 5-26

Insufficient end overlap.


A-610: Section 8.3.2.8, Fig. 8-37

End Overlap

Dewetting

Nonwetting

Excess Solder

Insufficient Solder

Chip Components

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Defect, Class 1, 2, 3Reference A-610: Section 5.2.8

Disturbed Joint

An escape of air or gas (out-gassing) during the soldering

process through tiny “pin” holes. Allowable condition as

long as minimum soldering requirements have been met.

Acceptable Class 1 Process Indicator

Class 2, 3Reference


Fractured or cracked solder joint.

Defect, Class 1, 2, 3 Reference A-610: Section 5.2.9

One end of the component termination is completely

lifted off the land.

Defect, Class 1, 2, 3 Reference

A-610: Section 8.3.2.9.4

Lead free solder joints typi-cally have a grainy or dull appearance.

Acceptable, Class 1, 2, 3 Reference A-610: Section 5.1

Lead Free Joint

Tombstoning

Fractured/Cracked Joint

Pinholes

BlowholesLarger holes (than pinholes) in the solder joint allowing

voids, or trapped gasses, to escape from the solder

joint. Allowable condition as long as minimum soldering

requirements have been met.


Class 2, 3Reference


Pb

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Any balls of solder that are not entrapped in a permanent coating, or attached to a metal contact, or violate mini-mum electrical clearance requirements.


Typically small balls of the original solder paste that

have splattered around the connection during reflow.

If violating minimum electrical clearance, or not encapsu-

lated, nor attached to a metal surface, then:


A-610: Section 5.2.7.1, Fig. 5-33

Any adhesive material in termination area is:

Acceptable Class 1 Process Indicator Class 2

Defect Class 3Note: Adhesive material

causing less than minimum end joint width is also a

Defect: Class 1, 2.

Reference A-610: Section 8.1

Mounting Adhesive on the Land

A connection of solder across conductors or lands that should not be joined.


Solder splashes that are not attached, entrapped, encapsulated, that impact form, fit or function, or that violate minimum electrical clearance.

Defect, Class 1, 2, 3Reference A-610: Section 5.2.7.3

Solder Splashes

Solder Bridging Solder Fines

Solder Balls

The solder paste had insuffi-cient heat to reflow properly.


A-610: Section 5,2.3, Fig. 5-15

Incomplete Reflow

Pb

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Acceptance Criteria


between the land and com-ponent lead is not specified.

Only a properly wetted fillet must be evident.

Heel Fillet Height (F)The heel fillet must extend up to

at least 50% the thickness of the component lead (T)*, as a

minimum fillet height.


J-Lead Components • Class 1

This photo represents an ideal

surface mount solder joint for

any class of J-lead component.

Notes: Solder joints are semi-transparent to show relationship between land and lead. Side Overhang, Dimension (A), must not violate minimum electrical clearance. The references below are applicable to the dimensional criteria for J-Lead components.


Target Condition

Acceptance Criteria

End Joint Width (C)The width of the solder joint at its narrowest point needs

to be a minimum of 50% lead width (W).

Heel Fillet Height (E)The solder may not touch the component body as a

maximum fillet height.

Side Joint Length (D)The length of the solder

joint at its narrowest point, has no minimum

requirement. Only a properly wetted fillet

must be evident.

Toe Overhang (B)The maximum distance the end

or tip of the lead may extend over the edge of the land is

not specified. Lead tip must not violate minimum electrical

clearance.

Side Overhang (A)The component lead may overhang

the side of the land a maximum of 50% the width of the lead (W).

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Acceptance Criteria

Solder Thickness (G)The minimum distance between the land and component lead is not specified. Only a properly

wetted fillet must be evident.

Heel Fillet Height (F)The heel fillet must extend up to

at least 50% the thickness of the component lead (T)*, as a

minimum fillet height.





J-lead component.



Target Condition

Acceptance Criteria

End Joint Width (C)The width of the solder joint at its nar-rowest point needs to be a minimum

of 50% lead width (W).



Side Joint Length (D)The length of the solder joint at

its narrowest point, must be a minimum of 150% the

width of the lead (W).

Toe Overhang (B)The maximum distance the end

or tip of the lead may extend over the edge of the land is

not specified. Lead tip must not violate minimum electrical clearance.

Side Overhang (A)The component lead may overhang the side of the land a maximum of

50% the width of the lead (W).

J-Lead Components

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Chip Components

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between the land and com-ponent lead is not specified.

Only a properly wetted fillet must be evident.

Heel Fillet Height (F)The minimum heel fillet height

must extend up to at least 100% of the Lead Thickness (T)*.*Including any measurement

for solder thickness (G).


This photo represents an ideal surface mount solder joint for any

class of J-lead component.



Acceptance Criteria

Target Condition

Acceptance Criteria

End Joint Width (C)The width of the solder joint at its narrowest point needs to be a minimum of 75% lead width

(W).



Side Joint Length (D)The length of the solder joint at

its narrowest point, must be a minimum of 150% the

width of the lead (W).

Toe Overhang (B)The maximum distance the end or tip of the lead may extend over the edge of the land is not specified. Lead tip must not violate minimum

electrical clearance.

Side Overhang (A)The component lead may overhang the side of the land a maximum of

25% the width of the lead (W).

J-Lead Components

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Chip Components

Class 1Class 2

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The following pages show photographs of some of the major sol-der defects and process indicators for surface mounted J-lead components.


Solder has not adhered to the land or termination. No

metallic bond.



Characterized by uneven surface from movement in the

joint while cooling.


A-610: Section 5.2.8, Fig. 5-43






Dewetting

Solder touches the component body.

Defect, Class 1, 2, 3 Reference A-610: Section 8.3.7.5, Fig. 8-131

Solder fails to meet minimum fillet height. No evidence of properly wetted fillet.

Defect, Class 1, 2, 3 Reference A-610: Section 8.3.7.6, Fig. 8-136

Insufficient Solder

Excess Solder Disturbed Joint

Nonwetting

J-Lead Components

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Chip Components

Class 1Class 2

Gull Wing Com

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voids, or trapped gasses, to escape from the solder

joint. Allowable condition as long as minimum soldering

requirements have been met.

Acceptable, Class 1 Process Indicator, Class

2, 3Reference

A-610: Section 5.2.2, Fig. 5-10

A connection of solder across conductors that should not be

joined.


A-610: Section 5.2.7.2, Fig. 5-35


Defect, Class 1, 2, 3Reference A-610: Section 5.2.9, Fig. 5-46

One lead, or series of leads on a component, is out of alignment (coplanarity), and prevents formation of a proper solder joint.

Defect, Class 1, 2, 3Reference A-610: Section 8.3.7.8, Fig. 8-138

Lead free solder joints typically have a grainy or dull appearance, or greater wetting contact angles.

Acceptable, Class 1, 2, 3Reference A-610: Section 5.1

Lead Free Joint

Open Connection


Incomplete Reflow

Blowholes

The solder paste had insuffi-cient heat to reflow properly.


A-610: Section 5.2.3, Fig. 5-14

Solder Bridging

Pb

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Class 3Photos

Solder Thickness (G)The minimum distance between the land and component lead is not specified. Only a properly

wetted fillet must be evident.

Heel Fillet Height (F)There is no minimum fillet

height requirement. Only a properly wetted fillet

must be evident.

Gull Wing Components • Class 1

This photo represents an ideal surface mount solder

joint for any class of Gull Wing

component.

Notes: Solder joints are semi-transparent to show relationship between land and lead. Side Overhang, Dimension (A), must not violate minimum electrical clearance. The references below are applicable to the dimensional criteria for Gull Wing components.


Acceptance Criteria

Target Condition

End Joint Width (C)The width of the solder joint at its

narrowest point needs to be at least 50% lead width (W), as a

minimum requirement.

Heel Fillet Height (E)Solder may extend to the

top bend of the lead, or knee, but not touch the compo-

nent body or end seal as a maximum fillet height.

Note: Solder may touch the body of a plastic SOIC

(family of components).

Side Joint Length (D)The length of the solder joint

at its narrowest point, must be a minimum of the lead width

(W), or 0.5 mm (0.02 in.), whichever is less.

Toe Overhang (B)The end or tip of the lead extending

over the edge of the land must not violate minimum electrical clearance

as a maximum condition.


the side of the land a maximum of 50% lead width (W), or 0.5 mm

(0.02 in.), whichever is less.

Acceptance Criteria

Class 2Gull W

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Chip Components

J-Lead Components

Class 1Class 3

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Heel Fillet Height (F)Small T: Where lead thickness

(T) is 0.4 mm or less, minimum heel fillet height is equal to (T)*,

measured at the toe.

Large T: Where (T) is greater than 0.4 mm, Dim. F is a minimum of 50% (T)*.


Gull Wing Components • Class 2

This photo represents an ideal

surface mount solder joint for any class of Gull Wing

component.

Notes: Solder joints are semi-transparent to show relationship between land and lead. Side Overhang, Dimension (A), must not violate minimum electrical clearance. Solder Thickness, or Dimension (G) is not specified for Class 2, only a properly wetted fillet must be evident. Please see Gull Wing, Class 1, for Dim. (G) picture. The references below are applicable to the dimensional criteria for Gull Wing components.


Acceptance Criteria

Target Condition




Heel Fillet Height (E)Solder may extend to the top

bend of the lead, or knee, but not touch the component

body or end seal as a maximum fillet height.

Note: Solder may touch the body of a plastic SOIC (family of components).

Side Joint Length (D)Long Foot—When foot length (L) is equal to or greater than

three lead widths (W), side joint length (D) must be

a minimum of 3 (W) or 75% (L), whichever is longer.

Toe Overhang (B)If foot length (L) is greater than 3 land

widths (W), then the tip of the lead extending over the edge of the land must not violate minimum electrical

clearance (MEC) as a maximum condition. If (L) is less than 3 (W), any

amount of toe overhang is a defect.




Acceptance Criteria

Side Joint Length (D)Short Foot—If foot length (L) is less than 3 (W), then minimum (D) is 100% (L).

Gull Wing Com

ponentsClass 3

3332

Gull

Win

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sCl

ass 3


Chip Components

J-Lead Components

Class 1Class 2

PhotosAr

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otos Gull Wing Components • Class 3

This photo represents an ideal surface mount solder

joint for any class of Gull Wing

component.

Notes: Solder joints are semi-transparent to show relationship between land and lead. Side Overhang, Dimension (A), must not violate minimum electrical clearance. Solder Thickness, or Dimension (G) is not specified for Class 3, only a properly wetted fillet must be evident. Please see Gull Wing, Class 1, for Dim. (G) picture. The references below are applicable to the dimensional criteria for Gull Wing components.


Acceptance Criteria

Target Condition




Toe Overhang (B)If foot length (L) is greater than 3 land

widths (W), then the tip of the lead extending over the edge of the land must not violate minimum electrical

clearance (MEC) as a maximum condition. If (L) is less than 3 (W), any

amount of toe overhang is a defect.




Acceptance Criteria

Heel Fillet Height (F)The minimum heel fillet height

must be at least as high as Lead Thickness (T)* at

connection side.*Including any measurement

for solder thickness (G).

Heel Fillet Height (E)Solder may extend to the top

bend of the lead, or knee, but not touch the compo-

nent body or end seal as a maximum fillet height.

Note: Solder may touch the body of a plastic SOIC (family of components).

Side Joint Length (D)Long Foot—When foot length (L) is equal to or greater than

three lead widths (W), side joint length (D) must be

a minimum of 3 (W) or 75% (L), whichever is longer.

Side Joint Length (D)Short Foot—If foot length (L) is less than 3 (W), then minimum (D) is 100% (L).

Gull Wing Com

ponentsPhotos

3534

Gull

Win

g Co

mpo

nent

sPh

otos


Chip Components

J-Lead Components

Class 1Class 2

Class 3Ar

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rray

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Gull Wing Solder ConditionsThe following pages show photographs of some of the major solder defects and process indicators for surface mounted Gull Wing components.


Solder fails to meet minimum heel fillet height. No evidence of properly wetted fillet.


Solder touches body of plastic SOIC (family of components).

Acceptable, Class 1, 2, 3Notes: Solder that touches the body of a ceramic or metal component is a Defect Class 1, 2, 3. Solder that touches the body of a plastic component outside the SOIC family, is Acceptable Class 1, Defect Class 2, 3.

Reference A-610: Section 8.3.5.5






Characterized by uneven surface from movement in the

joint while cooling.



Solder has not adhered to the land or termination. No

metallic bond.



Nonwetting

Disturbed Joint

Dewetting

Excess Solder

Insufficient Solder

Gull Wing Com

ponentsPhotos

3736

Gull

Win

g Co

mpo

nent

sPh

otos


Chip Components

J-Lead Components

Class 1Class 2

Class 3Ar

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rray

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Defect, Class 1, 2, 3Reference A-610: Section 5.2.9

One lead, or series of leads on a component, is out of alignment (coplanarity), and prevents formation of a proper solder joint.


A connection of solder across conductors that should not be joined.


A-610: Section 5.2.7.2

Any balls of solder that are not entrapped in a perma-

nent coating, or attached to a metal contact, or violate

minimum electrical clearance requirements.


A-610: Section 5.2.7.1, Fig. 5-31

An escape of air or gas (out-gassing) during the soldering

process through tiny “pin” holes. Allowable condition as

long as minimum soldering requirements have been met.


Class 2, 3Reference

A-610: Section 5.2.2, Fig. 5-12

Lead free solder joints typically have a grainy or dull appearance.

Acceptable, Class 1, 2, 3Reference A 610: Section 5.1

Lead Free Joint Pinholes

Solder Balls

Solder Bridging

Open Connection


Pb


Class 1Class 2

Class 3

3938

Area

Arra

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ass 3

Chip Components

J-Lead Components

Gull Wing Com

ponentsPhotos

Chip

Com

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nts

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ing

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os

Solder BallsBGA components come with various land patterns, but all

include circular solder balls that are pre-formed onto the lands of the BGA. Once soldered onto the

board only the external row of solder balls may be visible.

Ball Grid Arrays (BGA) • Class 1, 2, 3Target Condition

MisalignmentVisual registration between

existing legends on the surface of the board and the BGA

component outline should not be uneven or misaligned. This is only a defect if the solder

ball offsets violate minimum electrical clearance.

Shows target solder connections

along the perimeter (visible) row

underneath a BGA.

Note the complete wetting of the solder balls to the land, forming continuous, evenly rounded and

evenly spaced connections.

References: A-610F: 8.3.12 See Table 8-13

for Collapsing Balls. For Non-Collapsing Balls: Table 8-14, and the latest amendment to A-610F.

Acceptance Criteria

Solder BridgingVisual or X-Ray evidence of solder bridging is a defect for any class

of product.

VoidsLight areas on X-Rays within an individual ball indicate voiding.

More than 30% voiding of any collapsable solder ball in the X-Ray image is a defect

for Classes 1-3.

Incomplete WettingSolder balls that have reflowed but are not wetted to the land are con-sidered a defect for all classes of products. This is also called “head

in pillow” because of the visual similarity.

Non-wettingSolder joints that are not wetted to

either the lands on the board or the component are considered a

defect for Classes 1-3.

Acceptance Criteria

FracturesComplete or partial cracks in

the solder balls are considered a defect for all three classes.


Class 1Class 2

Class 3

4140

Area

Arra

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nent

sCl

ass 1

Clas

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ass 3

Chip Components

J-Lead Components

Gull Wing Com

ponentsPhotos

Chip

Com

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os

QFN ComponentsCommonly called QFN or Quad

Flat No Lead. Terminations typically extend from underneath

the component to the outside perimeter on all four sides.

Wetting of QFN terminations and lands is evident.

Alignment is accurate and

evenly spaced.

Component Types

Target Condition

DFN ComponentsCommonly called DFN or Dual

Flat No-Lead. Terminations typically extend from under-neath the component to the

outside perimeter — projecting from two sides only.

Shows target solder connection for BTC. Note concave solder

fillet with complete wetting to the top of the toe termination.

References: A-610F: 8.3.13, Table 8-16

Bottom Termination (BTC) • Class 1, 2, 3

End Joint Width (C)The minimum width of the solder

joint (C) must be at least 50% of the termination width (W) for Class

1. 75% of the toe width (W) is the minimum for Class 2-3

(as shown).

Toe (End) Fillet Height (F)The solder fillet (F) does not

need to extend up onto the face of the toe or end of the

termination. Evidence of wetting between the land and termi-

nation (G) is the minimum requirement for fillet height.

Toe Overhang (B)Any amount of toe overhang (B) is a defect for Cass 1, 2, 3 (as

shown in cross section view).

Side Overhang (A)Overhang is a maximum of 50%

the width of the toe/termination (W) for Class 1, and 25% (W) as

a maximum for Class 2, 3 (as shown).

Acceptance Criteria

Toe TerminationsBoth QFN and DFN

components typically have a toe termination that extends out

to the edge of the component.

Pb

This reference guide does not take precedence over, or replace the requirements from any IPC Standard or Specification. While every effort has been made to represent applicable portions of the IPC-A-610F document, this guide may not cover all related requirements and is not intended for use as an industry consensus standard. IPC disclaims any warranties or guarantees, expressed or implied, and shall not be held liable for damages of any kind in connection with the information set forth in DRM-SMT-F.

If you have comments or suggestions regarding this Training and Reference Guide, please contact:

IPC Training P.O. Box 389

Ranchos de Taos, NM 87557 +1 847.597.2940 (tel.) +1 575.758.7938 (fax)

[email protected]

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